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991.
In this paper, concepts of quasi-finitely separating maps and quasi-approximate identities are introduced. Based on these concepts, QFS-domains and quasicontinuous maps are defined. Properties and characterizations of QFS-domains are explored. Main results are: (1) finite products, nonempty Scott closed subsets and quasicontinuous projection images of QFS-domains, as well as FS-domains, are all QFS-domains; (2) QFS-domains are compact in the Lawson topology; (3) An L-domain is a QFS-domain iff it is an FS-domain, iff it is compact in the Lawson topology; (4) Bounded complete quasicontinuous domains, in particular quasicontinuous lattices, are all QFS-domains. 相似文献
992.
993.
Decays of both η and η' provide very useful information in our understanding of low-energy QCD,and experimental signatures for these decays would be extremely helpful at BES-Ⅲ.The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond.The sensitivities of the measurements of η and η' decays are discussed at BES-Ⅲ,in which the η and η' mesons are produced in the ψ decays. 相似文献
994.
Let M be an n-dimensional submanifold in the simply connected space form F n+p (c) with c + H 2 > 0, where H is the mean curvature of M. We verify that if M n (n ≥ 3) is an oriented compact submanifold with parallel mean curvature and its Ricci curvature satisfies Ric M ≥ (n ? 2)(c + H 2), then M is either a totally umbilic sphere, a Clifford hypersurface in an (n + 1)-sphere with n = even, or ${\mathbb{C}P^{2} \left(\frac{4}{3}(c + H^{2})\right) {\rm in} S^{7} \left(\frac{1}{\sqrt{c + H^{2}}}\right)}$ C P 2 4 3 ( c + H 2 ) in S 7 1 c + H 2 . In particular, if Ric M > (n ? 2)(c + H 2), then M is a totally umbilic sphere. We then prove that if M n (n ≥ 4) is a compact submanifold in F n+p (c) with c ≥ 0, and if Ric M > (n ? 2)(c + H 2), then M is homeomorphic to a sphere. It should be emphasized that our pinching conditions above are sharp. Finally, we obtain a differentiable sphere theorem for submanifolds with positive Ricci curvature. 相似文献
995.
Min Dai Zhong Zhang Jingtao Zhu Xiaoqiang Wang Jing Xu Xiuhua Fu Liang Bai Qiushi Huang Zhanshan Wang Lingyan Chen 《中国光学快报(英文版)》2009,7(8)
from layer to layer during multilayer growing. The variation of the reflectivity and interface roughness with bi-layer number is accurately explained by the presented real-structure model. 相似文献
996.
Pearlescent coatings become highly popular to the modern generation of color rendering materials due to their unique color effect. However, it is quite challenging to evaluate its color appearance by traditional color measurement. A low-cost camera is a highly efficient device for multi-geometry color appearance estimation for pearlescent bottles, which has been achieved through the camera characterization, sample image capturing, and then mathematical transforming from RGB (red, green, and blue) values to color appearance attributes based on the color appearance model of CIECAM02. A tele-spectroradiometer for physical measurement together with visual assessment is applied for comparison with the camera method to evaluate the accuracy of camera predictions and discuss the applicability of CIECAM02. The experimental results indicate that the camera data have strong correlation with the physical measurement and also fit well with visual data except for a slight slope shift existing in lightness due to a divinable psychophysical magnitude variation for spatial-dependent color samples. Hence it is feasible to estimate the color appearance of pearlescent bottles using a digital camera. 相似文献
997.
Hui-Zhong Xu Xiao Chen Jing Hua Jun-Ming Liu 《Journal of magnetism and magnetic materials》2009,321(22):3698-3701
Micromagnetic simulations based on the Landau–Lifshitz–Gilbert equation are presented to study spin-polarized current induced magnetization switching in asymmetric nanoring-shaped magnetic tunnel junctions. The results show that in a nanoring with an intermediate eccentric distance S, the critical switching voltage VC reaches the minimum whose magnitude is less than half of the voltage for a symmetric nanoring. In addition to the spin-transfer torque, the current induced Ampère field is found to play a crucial part in the switching process. Analysis is given to explain the existence of such an energy valley that leads to the minimal voltage. 相似文献
998.
We investigate the effect of the polarization state of the input pulses on the visible emissions in the anomalous dispersion region of polarization-maintaining photonic crystal fiber (PM-PCF), by using ~100 fs pump pulses whose central wavelength (1064 nm) is close to the second zero dispersion wavelength (1100 nm) of the fiber, where the soliton fission mechanisms play an important role. The experimental results show that the phase-matching two-color dispersive wave emission, one at 582 nm and the other at 600 nm, is polarization-dependent and frequency shift results from the different dispersion characteristics along the two orthogonal principal axes of PM-PCF. Furthermore, it is observed for the first time that the variation of the linear input polarization angles in 45° region almost has no influence on the output spectral profiles, and the break variation of the output spectrum exists when the angle between the polarization of the linear incident pulse and the fast-axis or the slow-axis of PM-PCF is 45°, which are attributed to the coupling between the two polarization modes in high birefringent PM-PCF. 相似文献
999.
刘玉 《纯粹数学与应用数学》2007,23(2):255-261
刻画了2×2全矩阵代数保立方幂等映射,利用保立方幂等映射象与原象矩阵对应元素相等这个特点计算出相应的结果,得出特征不等于2,3,5域上2×2全矩阵代数保立方幂等单射的一个具体的刻画. 相似文献
1000.
Xu Chun Song E. Yang Rong Ma Hai Fang Chen Zhong Li Ye Min Luo 《Applied Physics A: Materials Science & Processing》2009,94(1):185-188
ZnWO4 nanorods with a bundle-like structure were synthesized at 180°C for 12 h by a hydrothermal technology from Na2WO4⋅2H2O and ZnSO4⋅7H2O in the presence of sodium dodecyl sulfate (SDS). The as-synthesized bundle-like structure of ZnWO4 nanorods was characterized by various techniques: TEM, XRD and EDS. The luminescence properties of the bundle-like structure
of the ZnWO4 nanorods were investigated by photoluminescence (PL) spectroscopy. 相似文献